What physical examination should be performed in a patient suspected of colorectal cancer?

Physical Examination for Suspected Colorectal Cancer

The physical examination for suspected colorectal cancer must include a digital rectal examination with rigid proctoscopy and biopsy, along with a complete abdominal examination to assess for masses, hepatomegaly, and signs of metastatic disease. 1

Essential Components of Physical Examination

Digital Rectal Examination (DRE) with Rigid Proctoscopy

• Clinical rectal examination with rigid proctoscopy is mandatory for diagnosis and must include biopsy for histopathological confirmation. 1, 2
• Rigid proctoscopy allows precise measurement of tumor distance from the anal margin, which is critical for classification: tumors ≤15 cm from the anal verge are classified as rectal cancer, while more proximal tumors are colonic. 1, 2, 3
• This measurement directly determines treatment strategy, as rectal cancers often require neoadjuvant therapy while colon cancers typically do not. 2, 3

Abdominal Examination

• Palpate for abdominal masses, which have high predictive value for colorectal cancer and mandate investigation even without strong published evidence. 4
• Assess for hepatomegaly or palpable liver masses suggesting metastatic disease. 1
• Evaluate for signs of bowel obstruction including distension, absent bowel sounds, or peritoneal signs (guarding, rebound tenderness). 5
• In thin individuals with low BMI, the colon may be more readily palpable due to reduced subcutaneous fat, but palpability alone without associated symptoms does not indicate pathology. 5

General Physical Assessment

• Complete physical examination should assess for signs of anemia (pallor, tachycardia), cachexia, and lymphadenopathy. 1
• Examine for signs of metastatic disease including supraclavicular lymphadenopathy and ascites. 1

Critical Pitfalls to Avoid

Measurement Accuracy

• Always use rigid proctoscopy rather than flexible sigmoidoscopy for measuring tumor distance from the anal margin, as this measurement determines whether the tumor is classified as rectal (requiring potential neoadjuvant therapy) versus colonic. 1, 2
• Misclassifying high rectal cancer (10-15 cm) as mid-rectal cancer leads to overtreatment with unnecessary preoperative chemoradiotherapy. 3

Biopsy Requirement

• Never defer biopsy based on clinical suspicion alone—histopathological confirmation is required before initiating any treatment. 1, 2

Symptom Duration

• Do not assume that longer symptom duration correlates with more advanced disease; studies show no association between symptom duration and tumor stage. 6
• The median duration of symptoms before diagnosis is 14 weeks, so "chronic" gastrointestinal symptoms should not falsely reassure you. 6

Symptom Assessment During Physical Examination

While performing the physical exam, correlate findings with key symptoms:

• Rectal bleeding (58% of cases) and change in bowel habits toward increased looseness or frequency (51%) have the highest predictive value for colorectal cancer. 4, 6
• Abdominal pain alone (52% of cases) has limited predictive value due to high community prevalence. 4, 6
• Iron deficiency anemia (57% of cases) and occult bleeding (77%) are common findings that mandate investigation despite limited published evidence on their predictive value. 4, 6

Location Prediction Based on Clinical Findings

Physical examination findings can help predict tumor location:

• Distal tumors (below splenic flexure) are more likely with: rectal bleeding, constipation, higher hemoglobin levels, and absence of proximal symptoms (anorexia, nausea, vomiting, abdominal pain, fatigue). 6
• This prediction rule has 93% sensitivity and 47% specificity for distal location, which may guide the urgency and type of endoscopic investigation. 6